virtual office for mac team?

Can anyone advise me how to set up 4 or 5 macs to have access to a common database - contacts, documents, calender etc. We don't have our own server and aren't in the same place so need to access it online. We have some space on a server for our website, but I don't really know much more than that! Can anyone advise! We're a small not for profit initiative trying to work together better and don't know how to do it!

Do you know their IP addresses? Because if you do you could connect to their networks and stream data. Or you could use Apple's remote desktop which allows users to connect to a terminal for mutlchanneling protocols. The server though listens in on tcp port 3389. Do you have a .mac account because if you do you could set up 2 or 3 of the users but have to pay for the additional users. I think that is right I'm just thinking as much as I can to help you. hope this works if it doesn't I will do some more thinking.